Worksheet: Calculating pH

In this worksheet, we will practice describing the pH scale as a logarithmic measure of acid content and calculating values of pH.

Q1:

The hydronium ion concentration of vinegar is approximately 4.0×10 M. What is the corresponding value of the pH?

Q2:

What is the hydronium ion concentration of blood, the pH of which is 7.3 (slightly alkaline)?

A4.1 M

B7.3 M

C5.0×10 M

D2.0×10 M

E6.7×10 M

Q3:

Water exposed to air contains carbonic acid, HCO23, due to the reaction between carbon dioxide and water, as shown.
CO()+HO()HCO()2223aqlaq
Air-saturated water has a hydronium ion concentration caused by the dissolved CO2 of 2.0×10 M, about 20 times larger than that of pure water. What is the pH of the solution at 25∘C?

Q4:

What is the pH of stomach acid, which is a solution of
HCl with a hydronium ion concentration of
1.2×10 M, to
1 decimal place?

Q5:

What is the hydronium ion concentration of a solution with a pH of −1.07?

Q6:

To 2 decimal places, what is the pH of 0.200 MHCl at 25∘C? Assume that HCl ionizes completely.

Q7:

Coffee has a pH of about 5.1. Calculate the hydronium ion concentration of
coffee at 25∘C.
Express your answer in scientific notation, rounded to 1 decimal places.

A7.9×10 M

B1.3×10 M

C1.2×10 M

D6.3×10 M

E1.6×10 M

Q8:

Calculate to 3 significant figures the hydronium ion concentration in a solution with a pH of 6.52. Give your answer to 2 decimal places and in scientific notation.

A5.06×10 M

B3.31×10 M

C8.95×10 M

D3.02×10 M

E6.79×10 M

Q9:

Lime juice has a pH of about 2.3. Calculate, to 1 decimal place and in scientific notation, the hydronium ion concentration of lime juice at 25∘C.

A2.0×10 M

B4.5×10 M

C9.3×10 M

D2.2×10 M

E5.0×10 M

Q10:

What is the pH of 3.0 MHNO3 at 25∘C? Assume that HNO3 ionizes completely.

Q11:

What is the pH of 0.000259 MHClO4 at 25∘C? Assume that HClO4 ionizes completely.